Traffic scanning lidar

ABSTRACT

A system for determining the speed and position of objects comprises a beam source, a transmit reflection device, a beam receiver, a receive reflection device, and a controller. The beam source may generate a beam. The transmit reflection device may reflect the beam at the objects and may include a plurality of transmit faces with each transmit face oriented at a different angle and operable to reflect the beam at a different height. The beam receiver may detect the beam. The receive reflection device may include a plurality of receive faces with each receive face oriented at a different angle and operable to focus the beam reflected from objects at different heights onto the beam receiver. The controller may determine the position of the objects over time and calculate the speed of the objects based on a change in the position of the objects.

RELATED APPLICATIONS

The present application is a continuation patent application and claimspriority benefit, with regard to all common subject matter, ofearlier-filed U.S. patent application Ser. No. 13/085,994, entitled“TRAFFIC SCANNING LIDAR,” filed Apr. 13, 2011, and issued Jan. 14, 2014,as U.S. Pat. No. 8,629,977 (“the '977 patent”). The '977 patent is anon-provisional utility application and claims priority benefit, withregard to all common subject matter, of earlier-filed U.S. ProvisionalPatent Applications entitled “TRAFFIC SCANNING LIDAR”, Ser. No.61/324,083, filed Apr. 14, 2010, and “TRAFFIC SCANNING LIDAR”, Ser. No.61/405,805, filed Oct. 22, 2010. The identified earlier-filed patent andapplications are hereby incorporated by reference into the presentapplication in their entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to systems for monitoring vehiclevelocities. More particularly, the invention relates to systemsmonitoring vehicle velocities using scanning light detection andranging.

2. Description of the Related Art

Traffic control that includes monitoring the velocities of vehicles onthe roadways may be implemented by law enforcement officers usingvarious devices and systems, such as Doppler radar and LIDAR. Dopplerradar operates in the microwave frequencies, typically X, K, and Kaband, and transmits a continuous or almost continuous wave and measuresthe speed of vehicles by receiving the reflected signal and using theDoppler principle. Typical Doppler radars can be operated from astationary point or can be mounted in a law enforcement vehicle andoperated while the law enforcement vehicle is moving. They are able tobe used in a moving situation because the beamwidth is wide, typically20 degrees, and therefore do not have to be pointed accurately at thevehicle being measured. But this feature is also a problem because whenthere are multiple vehicles in the beam, the operator does not knowwhich vehicle is being measured. In the moving mode the Doppler radarsubtracts out the speed of the law enforcement vehicle on which it ismounted.

Light detection and ranging (LIDAR) uses a laser pulse and determinesthe vehicle speed by performing distance time calculations based on thetravel time of the reflected light pulse. Because the LIDAR has a verynarrow beam, it is very selective of the vehicle being measured evenwhen there are several vehicles within range. But this is also adisadvantage in its usage because the operator must carefully aim theLIDAR at the vehicle, and therefore, it can only effectively be used instationary applications. The moving application has too much motion tokeep it aimed properly.

SUMMARY OF THE INVENTION

Embodiments of the present invention solve the above-mentioned problemsand provide a distinct advance in the art of systems for monitoringvehicle velocities. More particularly, embodiments of the inventionprovide a system that is operable to sweep a beam across a field of viewat varying heights to detect the speed of a plurality of objects, suchas motor vehicles, at the same time.

Embodiments of a system for detecting the speed and position of objectscomprise a beam source, a transmit reflection device, a beam receiver, areceive reflection device, and a controller. The beam source maygenerate a beam. The transmit reflection device may reflect the beam atthe objects and may include a plurality of transmit faces with at leasta portion of the transmit faces oriented at a different angle andoperable to reflect the beam at a different height. The beam receivermay detect the beam. The receive reflection device may include aplurality of receive faces with at least a portion of the receive facesoriented at a different angle and operable to focus the beam reflectedfrom objects at different heights onto the beam receiver. The controllermay determine the position of the objects over time and calculate thespeed of the objects based on a change in the position of the objects.

Additional embodiments of a system for detecting the speed and positionof objects comprise a beam source, a transmit device, a beam receiver, areceive device, and a controller. The beam source may generate a beam.The transmit device may sweep the beam at the objects through a knownangle in the horizontal direction and a known angle in the verticaldirection. The beam receiver may detect the beam. The receive device mayfocus the beam reflected from objects onto the beam receiver. Thecontroller may determine the position of the objects over time andcalculate the speed of the objects based on a change in the position ofthe objects.

Various embodiments of the present invention may include a transceivingreflection device for use with a light detection and ranging system. Thetransceiving reflection device comprises a transmit reflection deviceand a receive reflection device. The transmit reflection device mayreflect a beam from a beam source into a space in which objects may bepresent and may include a transmit base, a transmit upper stage, and aplurality of transmit faces. The transmit upper stage may be spacedapart from and parallel to the transmit base. The transmit faces may bepositioned in a circle between the transmit base and the transmit upperstage with at least a portion of the transmit faces oriented at adifferent angle therebetween. The receive reflection device may focusthe beam onto a beam receiver and may include a receive base, a receiveupper stage, and a plurality of receive faces. The receive base may becoupled to the transmit base. The receive upper stage may be spacedapart from and parallel to the receive base. The receive faces may bepositioned in a circle between the receive base and the receive upperstage with at least a portion of the receive faces oriented at adifferent angle therebetween.

This summary is provided to introduce a selection of concepts in asimplified form that are further described below in the detaileddescription. This summary is not intended to identify key features oressential features of the claimed subject matter, nor is it intended tobe used to limit the scope of the claimed subject matter. Other aspectsand advantages of the present invention will be apparent from thefollowing detailed description of the embodiments and the accompanyingdrawing figures.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

Embodiments of the present invention are described in detail below withreference to the attached drawing figures, wherein:

FIG. 1 is a block diagram of a system for determining the speed ofobjects constructed in accordance with various embodiments of thepresent invention;

FIG. 2 is a diagram of a frame that is scanned by the system;

FIG. 3 is a diagram of the frame depicting the sweeping of a beam withinthe frame;

FIG. 4 is a perspective view of a housing operable to house at least aportion of the system;

FIG. 5 is a perspective view of the system with the outer walls of thehousing removed;

FIG. 6 is a perspective view of the system of FIG. 5 with a portion of atransceiving reflection device removed to expose its interior;

FIG. 7 is a perspective view of the housing with a portion of theexterior walls removed to illustrate the system transmitting andreceiving the beam;

FIG. 8 is a front view of the transceiving reflection device including atransmit reflection device and a receive reflection device;

FIG. 9 is a perspective view of a transmit device including the transmitreflection device;

FIG. 10 is a perspective view of a receive device including the receivereflection device;

FIG. 11 is a sectional view of the transceiving reflection device;

FIG. 12 is a perspective view of an alternative embodiment of thetransmit device and the receive device;

FIG. 13A is an overhead view of a law enforcement vehicle utilizing thesystem to determine the speed of objects on a roadway;

FIG. 13B is an overhead view of the law enforcement vehicle utilizingthe system to determine the speed of objects on the roadway;

FIG. 14 is a graph of raw data from beams that are reflected by objectsand received by the system;

FIG. 15 is a graph of a histogram of beams received versus distance fromthe system;

FIG. 16 is a graph of a histogram of beams received from a potentialfirst object;

FIG. 17 is a graph of a histogram of beams received from a potentialsecond object;

FIG. 18 is a graph of a histogram of beams received from a potentialthird object; and

FIG. 19 is a graph of the position of potential objects over time.

The drawing figures do not limit the present invention to the specificembodiments disclosed and described herein. The drawings are notnecessarily to scale, emphasis instead being placed upon clearlyillustrating the principles of the invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The following detailed description of the invention references theaccompanying drawings that illustrate specific embodiments in which theinvention can be practiced. The embodiments are intended to describeaspects of the invention in sufficient detail to enable those skilled inthe art to practice the invention. Other embodiments can be utilized andchanges can be made without departing from the scope of the presentinvention. The following detailed description is, therefore, not to betaken in a limiting sense. The scope of the present invention is definedonly by the appended claims, along with the full scope of equivalents towhich such claims are entitled.

In this description, references to “one embodiment”, “an embodiment”, or“embodiments” mean that the feature or features being referred to areincluded in at least one embodiment of the technology. Separatereferences to “one embodiment”, “an embodiment”, or “embodiments” inthis description do not necessarily refer to the same embodiment and arealso not mutually exclusive unless so stated and/or except as will bereadily apparent to those skilled in the art from the description. Forexample, a feature, structure, act, etc. described in one embodiment mayalso be included in other embodiments, but is not necessarily included.Thus, the present technology can include a variety of combinationsand/or integrations of the embodiments described herein.

Embodiments of the present invention may provide a traffic scanninglight detection and ranging (LIDAR) system 10, as shown in FIG. 1, thatis operable to scan a field of view or a frame to determine the speedsof objects within the frame. The system 10 may broadly comprise a beamsource 12, a transmit device 14, a receive device 16, a beam receiver18, a controller 20, and a camera 22. The system 10 may optionallyinclude a display 24. The system 10 may further include a housing 26 tohouse the system 10 excluding the display 24.

The beam source 12 generally provides a source of electromagnetic (EM)radiation that is transmitted to at least one object 28, such as a motorvehicle as seen in FIGS. 13A-13B, and reflected back. Typically theradiation is swept or scanned over a space or a volume, such as aroadway setting, between the system 10 and the object 28 and may takethe form of a directed beam 30. As used herein, a “sweep” may refer tothe process of a beam 30 being moved, typically by rotation, through agiven angle. The field of view of the scan or the data associatedtherewith may be referred to as a “frame” 32, as seen in FIG. 2, and mayinclude a horizontal sweep angle θ and a vertical sweep angle Φ. In anexemplary frame 32, θ may range from approximately 24 degrees toapproximately 45 degrees, approximately 25.7 degrees to approximately 36degrees or may be approximately 28 degrees. Φ may range fromapproximately 5 degrees to approximately 9 degrees, approximately 6degrees to approximately 8 degrees or may be approximately 7 degrees.

The beam source 12 may include a laser 34, as is known in the art,operable to generate the beam 30. In some embodiments, the beam source12 may include a plurality of lasers that produce a plurality of beams30. An exemplary laser 34 may be configured to produce a pulsed outputwith a power that ranges from approximately 50 watts (W) toapproximately 100 W, approximately 70 W to approximately 80 W, or may be75 W. Each pulse may have a period that ranges from approximately 5nanoseconds (ns) to approximately 20 ns, approximately 7 ns toapproximately 15 ns, or may be approximately 10 ns. The pulse repetitionrate may range from approximately 50 kilohertz (kHz) to approximately100 kHz, approximately 70 kHz to approximately 90 kHz, or may beapproximately 80 kHz. The output of the laser 34 may be in the infrared(IR) range with a wavelength that ranges from approximately 700nanometers (nm) to approximately 1400 nm, approximately 850 nm toapproximately 950 nm, or may be approximately 905 nm. The beamdivergence may range from approximately 0.05 degrees to approximately0.15 degrees, approximately 0.07 degrees to approximately 0.12 degrees,or may be approximately 0.1 degrees in the horizontal direction. Thebeam divergence may range from approximately 0.5 degrees toapproximately 1.5 degrees, approximately 0.7 degrees to approximately1.2 degrees, or may be approximately 1 degree in the vertical direction.The beam source 12 may also include a collimating element 36, as shownin FIG. 5, which may collimate the output of the laser 34.

The system 10 may further include a beam source input 38 from thecontroller 20 to the beam source 12. The beam source input 38 maydetermine the operation of the beam source 12 such as energizing andde-energizing the beam 30, the width of the pulse, the power of theoutput, and the like.

The transmit device 14 generally directs or guides the beam 30 from thebeam source 12 in order to perform a sweep. The transmit device 14 maysweep the beam 30 across the field of view frame 32 in the horizontaland vertical directions. The transmit device 14 may include opticalcomponents such as lenses, mirrors, beam splitters, prisms, and the liketo perform actions on the beam source 12 output such as reflecting,refracting, diffracting, collimating, focusing, steering, and the like.

An exemplary embodiment of the transmit device 14 is shown in FIGS. 6-7,and may include a transmit reflection device 40 with a plurality oftransmit faces 42. The transmit reflection device 40 may include atransmit base 44 and a spaced-apart transmit upper stage 46. Thetransmit base 44 may be planar and somewhat disc shaped. The transmitupper stage 46 may also be planar and somewhat disc shaped with asmaller diameter than the transmit base 44. The transmit base 44 and thetransmit upper stage 46 may be roughly parallel with each other and havethe centers aligned. Both the transmit base 44 and the transmit upperstage 46 may include central openings.

The transmit faces 42 may be generally rectangular in shape with aplanar reflective surface. The transmit faces 42 may be located betweenthe transmit base 44 and the transmit upper stage 46 around thecircumference of the transmit base 44 and the transmit upper stage 46.In an exemplary embodiment, there may be twelve transmit faces 42positioned adjacent one another between the transmit base 44 and thetransmit upper stage 46. In alternative embodiments, there may be feweror more transmit faces 42 depending on, among other things, the desiredaspect ratio of the field of view frame 32. For example, fewer transmitfaces 42 may generally lead to a wider and shorter frame 32, while moretransmit faces 42 may generally lead to a narrower and taller frame 32.

Generally, at least a portion of the transmit faces 42 is oriented at adifferent angle. In the exemplary embodiment shown in the Figures, eachtransmit face 42 is oriented at a different angle. For example, thetransmit faces 42 may be oriented at consecutively changing angles withrespect to the transmit base 44 and the transmit upper stage 46.Specifically, the angle α between the transmit face 42 and the transmitupper stage 46, as seen in FIG. 11, may change. In general, the angle αfor any of the transmit faces 42 may range from approximately 25 degreesto approximately 65 degrees, from approximately 30 degrees toapproximately 60 degrees, or from approximately 40 degrees toapproximately 50 degrees. For individual transmit faces 42, there may bea difference in the angle α between consecutive transmit faces 42 thatranges from approximately 0.25 degrees to approximately 0.5 degrees ormay be approximately 0.375 degrees. Thus, the angle α for a firsttransmit face 42 may range from approximately 46.25 degrees toapproximately 47.5 degrees or may be approximately 46.875 degrees. Theangle α for a second transmit face 42 may range from approximately 46.0degrees to approximately 47.0 degrees or may be approximately 46.500degrees. The angle α for a twelfth transmit face 42 may range fromapproximately 42.0 degrees to approximately 43.5 degrees or may beapproximately 42.750 degrees. The difference between consecutivetransmit faces 42 may also influence the height of the frame 32. Forexample, a greater difference may generally lead to a greater height ofthe frame 32, while a lesser difference may generally lead to a shorterheight of the frame 32.

The transmit reflection device 40 may be positioned in proximity to thebeam source 12 such that the plane of the transmit base 44 and thetransmit upper stage 46 is roughly perpendicular to the axis of the beamsource 12. The beam 30 from the beam source 12 may strike the transmitfaces 42 roughly in the center of each face 42. The transmit reflectiondevice 40 may rotate about a central axis. As the transmit reflectiondevice 40 rotates, the beam 30 may reflect off each of the transmitfaces 42 in turn, creating one sweep for each transmit face 42. Sincethe transmit faces 42 are oriented at consecutively changing angles, thebeam 30 is swept at a consecutively changing height within the frame 32in order to create a raster scan.

Referring to FIG. 3, the reflection of the beam 30 off the firsttransmit face 42 creates a sweep at the top of the frame 32. Thereflection of the beam 30 off the second transmit face 42 creates asweep just below the first sweep. The reflection of the beam 30 off thethird transmit face 42 creates a sweep just below the second sweep. Thisprocess continues until the beam 30 is reflected off the twelfthtransmit face 42, and the transmit reflection device 40 has completedone rotation. As the transmit reflection device 40 continues to rotate,the beam 30 is reflected off the first transmit face 42 again and thebeam is swept across the top of the frame 32. The beam 30 may sweep fromthe bottom of the frame 32 to the top of the frame 32, depending on thedirection of rotation of the transmit reflection device 40 and the orderin which the transmit faces 42 are positioned within the transmitreflection device 40.

In an exemplary embodiment of the system 10, the transmit reflectiondevice 40 is rotated at a speed such that the beam 30 is swept toprovide 20 frames per second.

As can be seen in FIG. 3, the beam 30 overlaps itself on consecutivesweeps from consecutive transmit faces 42 in the vertical directionwithin the frame 32. In other words, a portion of one sweep may overlapa portion of the next sweep. For example, the lower portion of the firstsweep may overlap the upper portion of the second sweep. The lowerportion of the second sweep may overlap the upper portion of the thirdsweep. The overlap may continue until the twelfth sweep, wherein onlythe upper portion of the twelfth sweep overlaps the lower portion of theeleventh sweep. Then, the next transmit face 42 is the first transmitface 42, that generates the first sweep across the top of the frame 32.The overlap helps to ensure that the frame 32 is completely scanned andthat no objects 28 are missed because of a gap between sweeps.

The transmit reflection device 40 may be formed from lightweightmaterials such as lightweight metals or plastics. The transmit faces 42may be formed from reflective materials. Exemplary transmit faces 42 mayhave a reflectivity of greater than 97%. In some embodiments, thetransmit reflection device 40 may be formed from separate transmit faces42 that are joined to the transmit base 44 and the transmit upper stage46. However, in an exemplary embodiment, the transmit reflection device40, including the transmit base 44, the transmit upper stage 46, and thetransmit faces 42, is formed as a monolithic single unit from a plastic,perhaps injection molded, that is coated with a reflective material suchas gold or silver.

The transmit device 14 may alternatively be implemented with a prismassembly that refracts the beam 30 instead of reflecting it. A firstexemplary prism assembly is a Risley prism assembly 48 that comprises afirst wedge prism 50 and a second wedge prism 52, as seen in FIG. 12.With a beam 30 directed at the Risley prism assembly 48, the first wedgeprism 50 may be rotated at a greater rotational frequency than thesecond wedge prism 52. This rotation scheme may result in aspiral-shaped sweeping pattern being formed. Thus, the frame 32 may havea circular shape rather than a rectangular shape. Alternatively, theRisley prism assembly 48 may be directed to sweep the beam 30 in acriss-cross pattern or a lemniscate pattern.

A second exemplary prism assembly is similar to the Risley prismassembly 48 of FIG. 12 and includes a third wedge prism with a smallerdeflection angle than the first and second wedge prisms 50, 52. In thisembodiment, the first and second wedge prisms 50, 52 may rotate inopposite directions to each other and at the same speed. In the absenceof the third prism, the two prisms 50, 52 may receive the beam 30directed at one of the prisms 50, 52 and refract the beam 30 to form ahorizontal line sweep. The third prism may be positioned adjacent to andin line with the first and second wedge prisms 50, 52 such that thethird prism receives the beam output from the first two prisms 50, 52.The third prism may be rotated to refract the beam 30 in the verticaldirection. Thus, while the first and second prisms 50, 52 are rotatingat a constant speed, the third prism may be stationary while the beam 30performs a full horizontal sweep at a first height. Then, the thirdprism may rotate through a fixed angle and stop while the beam 30performs a full horizontal sweep at a second height, different from thefirst. The third prism may rotate again and stop while the beam 30performs a full horizontal sweep at a third height, different from thesecond. This process may repeat while the beam 30 sweeps at differentheights to scan a full frame 32. Alternatively, the third prism may berotated at a very slow speed compared to the rotation of the first andsecond prisms 50, 52.

The system 10 may also include a motor 54 to rotate the transmitreflection device 40. The motor 54 may include alternating current (AC),direct current (DC), stepper motors, and the like. An exemplary motor 54may include a 36-Volt (V) brushless DC motor capable of rotating from 0to 4,000 revolutions per minute (rpm).

The receive device 16 generally guides the beams 30 reflected from oneor more objects 28 toward the beam receiver 18. The receive device 16may, in various embodiments, include optical components such as lenses,lenslets, lens arrays, focal plane arrays, mirrors, beam splitters,prisms, and the like to perform actions on the reflected beams 30 suchas focusing, reflecting, refracting, diffracting, steering, andgenerally guiding the beams 30 to the beam receiver 18.

An exemplary embodiment of the receive device 16 is shown in FIGS. 8 and10, and may include a receive reflection device 55 with a plurality ofreceive faces 56, a planar disc-shaped receive base 58 with a centralopening, and a spaced-apart receive upper stage 60. The receive faces 56may be generally wedge-shaped and positioned adjacent one anotherbetween the receive base 58 and the receive upper stage 60. In theexemplary embodiment of FIGS. 8 and 10, there may be twelve receivefaces 56 used with the receive reflection device 55. Generally, thenumber of receive faces 56 matches the number of transmit faces 42.

Each receive face 56 may include an outer surface 62 with the shape of apartial circular paraboloid. As a geometric shape, the circularparaboloid has the property of reflecting rays that strike theparaboloid surface with a trajectory that is parallel to the centralaxis to a focal point within the paraboloid. Thus, the receive faces 56may be used to reflect beams 30 to a focal point FP, as seen in FIG. 11.The beams 30 may be those that were transmitted from the beam source 12and reflected off objects 28 such as motor vehicles. The focal point forthe beams 30 may be the beam receiver 18, discussed in more detailbelow.

Generally, at least a portion of the receive faces 56 is oriented at adifferent angle. In the exemplary embodiment shown in the Figures, eachreceive face 56 is oriented at a different angle. For example, the outersurface 62 of each receive face 56 may be oriented at consecutivelychanging angles with respect to the receive base 58. Specifically, theangle β between the central axis CA of the partial circular paraboloidof each receive face 56 and a vertical axis VA that is perpendicular tothe receive base 58, as seen in FIG. 11, may change. In general, theangle β for any of the receive faces 56 may range from approximately 60degrees to approximately 120 degrees, from approximately 75 degrees toapproximately 105 degrees, or from approximately 80 degrees toapproximately 100 degrees. For individual receive faces 56, there may bea difference in the angle β between consecutive receive faces 56 thatranges from approximately 0.5 degrees to approximately 1 degree or maybe approximately 0.75 degrees. Thus, the angle β for a first receiveface 56 may range from approximately 85.0 degrees to approximately 87.5degrees or may be approximately 86.25 degrees. The angle β for a secondreceive face 56 may range from approximately 86.0 degrees toapproximately 88.0 degrees or may be approximately 87.00 degrees. Theangle β for a twelfth receive face 56 may range from approximately 93.0degrees to approximately 96.0 degrees or may be approximately 94.50degrees. The change in the angle β for consecutive receive faces 56 maycorrespond to the change in the angle α for consecutive transmit faces42. In various embodiments, the change in angle β may be a multiple ofthe change in the angle α.

In operation, the receive reflection device 55 may rotate. Duringrotation, each receive face 56 may focus beams 30 reflected from objects28 at varying angles of rotation. Furthermore, each consecutive receiveface 56 may focus beams 30 reflected from objects 28 at varying angleswith respect to the horizontal plane. For example, depending on thedirection of rotation of the receive reflection device 55, the receivefaces 56 may focus beams 30 reflected from objects 28 increasingly lowerin the frame 32 or increasingly higher in the frame 32. This operationof the receive reflection device 55 creates a raster scan for thereceived beams 30.

The receive device 16 may alternatively be implemented with a Risleyprism assembly 48 shown in FIG. 12. Beams 30 may be reflected fromobjects 28 in the roadway to the second prism 52 and travel through theassembly 48 to a beam splitter (not shown). The beam 30 is thenreflected from the beam splitter to the beam receiver 18.

Like the transmit reflection device 40, the receive reflection device 55may be formed from lightweight materials such as lightweight metals orplastics, and the receive faces 56 may be formed from reflectivematerials. Exemplary receive faces 56 may have a reflectivity of greaterthan 97%. In some embodiments, the receive reflection device 55 may beformed from separate receive faces 56 that are joined to the receivebase 58. However, in an exemplary embodiment, the receive reflectiondevice 55, including the receive base 58 and the receive faces 56, isformed as a monolithic single unit from a plastic, perhaps injectionmolded, that is coated with a reflective material such as gold orsilver.

In some embodiments, the receive reflection device 55 may coupled to thetransmit reflection device 40, such that the receive base 58 of thereceive reflection device 55 is connected to the transmit base 44 andthe transmit faces 42 are positioned opposite of and vertically alignedwith the receive faces 56. The combination of the receive reflectiondevice 55 and the transmit reflection device 40 may form a transceivingreflection device 64. In the exemplary embodiment of FIGS. 5-10, thetransmit reflection device 40 and the receive reflection device 55 areformed as a monolithic single unit from a metallic-coated plastic. Inaddition, the first receive face 56 is aligned with the first transmitface 42, the second receive face 56 is aligned with the second transmitface 42, and so forth, such that the twelfth receive face 56 is alignedwith the twelfth transmit face 42.

The motor 54 utilized for rotating the transmit reflection device 40 mayalso be used to rotate the receive reflection device 55. The motor 54may be positioned within the openings of the transmit upper stage 46 andthe transmit base 44 and the opening in the base of the receivereflection device 55. The motor 54 may include a shaft 66 that iscoupled to the receive upper stage 60 of the receive reflection device55, such that when the shaft 66 rotates, both the transmit reflectiondevice 40 and the receive reflection device 55 rotate as well.

The beam receiver 18 generally receives the reflected beams 30 that havebeen focused by the receive faces 56. The beam receiver 18 may includedevices or arrays of devices that are sensitive to IR radiation, such ascharge-coupled devices (CCDs) or complementary metal-oxide semiconductor(CMOS) sensor arrays, photodetectors, photocells, phototransistors,photoresistors, photodiodes, or combinations thereof. In an exemplaryembodiment, the beam receiver 18 includes a silicon avalanche photodiodewith a peak sensitivity at 905 nm, a bandwidth of 905 nm±40 nm, anactive area of 2 mm×2 mm, and a current gain of 200. The photodiode maybe coupled to a receiver circuit with a gain of 10⁶, an operationalfrequency range of 1 megahertz (MHz) to 100 MHz, and a comparatoroutput.

The beam receiver 18 may positioned in proximity to the receivereflection device 55 at the focal point of the receive faces 56. Thebeam receiver 18 may include a beam receiver output 68 that providesinformation corresponding to the reflected beams 30 to the controller20.

The controller 20 may execute computer programs, software, code,instructions, algorithms, applications, or firmware, and combinationsthereof. The controller 20 may include processors, microprocessors,microcontrollers, field-programmable gate arrays (FPGAs),application-specific integrated circuits (ASICs), combinations thereof,and the like, and may be implemented using hardware descriptionlanguages (HDLs), such as Verilog and VHDL. The controller 20 mayfurther include data storage components, which may comprise“computer-readable media” capable of storing the computer programs,software, code, instructions, algorithms, applications, or firmware. Thecomputer-readable media may include random-access memory (RAM) such asstatic RAM (SRAM) or dynamic RAM (DRAM), cache memory, read-only memory(ROM), flash memory, hard-disk drives, compact disc ROM (CDROM), digitalvideo disc (DVD), or Blu-Ray™, combinations thereof, and the like.

In an exemplary embodiment, the controller 20 includes a Kinetis K10microcontroller manufactured by Freescale of Austin, Tex., and an OMAP™4 microprocessor manufactured by Texas Instruments of Dallas, Tex. Someof the functions that the microcontroller handles include sending acontrol signal to the beam source 12 and sending a control signal to themotor 54. Some of the functions that the microprocessor handles includesending video information to the display 24, processing the receivedbeam 30 information, and calculating the speed of objects 28 within theframe 32.

The controller 20 may further include a timer circuit that is operableto measure the time of flight of the beam 30 or pulses of the beam 30.The timer may start when a pulse of the beam 30 is transmitted from thebeam source 12 and may stop when the pulse of the beam 30 is received bythe beam receiver 18.

In addition, the controller 20 may include an accelerometer or mayreceive the output of an external accelerometer to determine the motionof a vehicle in which the system 10 is implemented. The controller 20may also receive the pulse train output of the transmission of thevehicle.

In various embodiments, the controller 20 may be aware of the angle atwhich the transceiving reflection device 40 is rotating. Thus, thecontroller 20 may be aware of which transmit face 42 is reflecting thebeam 30 and which receive face 56 is focusing beams 30 onto the beamreceiver 18. Furthermore, the controller 20 may be aware of thehorizontal sweep angle θ and the vertical sweep angle Φ the beam 30 isbeing reflected from the transmit reflection device 40.

In some embodiments, the controller 20 may also receive MPEG4-encodeddata from the camera 22 and may determine velocity vector informationregarding objects 28 within the frame 32 based on the MPEG4 data.

The system 10 may further include components not shown in the figuressuch as inputs, outputs, and communication ports. Inputs may includeknobs, dials, switches, keypads, keyboards, mice, joysticks,combinations thereof, and the like. Outputs may include audio speakers,lights, dials, meters, printers, combinations thereof, and the like.Communication ports may be wired or wireless, electronic, optical, radiofrequency (RF), combinations thereof, and the like.

The camera 22 generally provides an image of the space or volume thatthe system 10 is scanning. An exemplary camera 22 may be a 1080phigh-definition camera capable of capturing 30 fps. The camera 22 mayinclude a camera output 70 that communicates video data to the display24. In some embodiments, the camera 22 may include an MPEG4 codec, as isknown in the art, to generate MPEG4-encoded data that may becommunicated to the controller 20 via a camera data output 72.

The display 24 generally displays the video image from the camera 22 aswell as information from the controller 20 regarding objects in theimage. The display 24 may include video monitors as are known in the artcapable of displaying moving or still video images in addition to textor graphical data within the same frame. Examples of the display 24 mayinclude cathode ray tubes (CRTs), plasma monitors, liquid crystaldisplay (LCD) monitors, light-emitting diode (LED) monitors, LED-LCDmonitors, combinations thereof, and the like.

In embodiments wherein the system 10 does not include the display 24,the system 10 may send data on a display output 74 to an externaldisplay or monitor.

The housing 26 may be of cubic or rectangular box shape with six walls:a top wall 76, a bottom wall 78, a left side wall 80, a right side wall82, a front wall 84, and a rear wall 86 that are coupled together in atypical box construction. The housing 26 may further include an internalframe 88 and an optical isolation plate 90. The housing 26 may beconstructed from plastics or lightweight metals, such as aluminum.

The camera 22 may be positioned on the exterior of the housing 26, suchas mounted on the exterior of the front wall 84 or the exterior of thetop wall 76. In other embodiments, the camera 22 may be positionedwithin the housing 26 adjacent a window or opening through which thecamera 22 captures video images. In still other embodiments, the camera22 may be positioned external to the housing 26.

The motor 54 may be mounted on the bottom wall 78 close to the centerthereof. Thus, the transmit reflection device 40 may face the bottomwall 78, while the receive reflection device 55 faces the top wall 76.The beam source 12 may also be mounted on the bottom wall 78 inproximity to the front wall 84, such that the collimating element 36 isaligned with one of the transmit faces 42.

The front wall 84 may include a receive window 92 and a transmit window94, both of which may be filled with a material, such as glass orglass-like material, that is transparent to electromagnetic radiation ata wavelength that ranges from approximately 700 nm to approximately 1400nm, approximately 850 nm to approximately 950 nm, or may beapproximately 905 nm. The receive window 92 may be positioned inproximity to the receive reflection device 55 such that it is alignedwith the receive faces 56. Beams 30 may reflect off objects 28 into thereceive window 92 and may be focused by the receive faces 56 onto thebeam receiver 18, as shown in FIGS. 7 and 11. The transmit window 94 maybe positioned in proximity to the transmit reflection device 40 suchthat it is aligned with the transmit faces 42. The beam source 12 maygenerate the beam 30 that reflects off the transmit faces 42 and travelsthrough the transmit window 94.

The internal frame 88 may include a first upright wall member 96 inproximity to the left side wall 80 and a second upright wall member 98in proximity to the right side wall 82, both of which are coupled to thebottom wall 78. The frame 32 may also include a cross beam 100 coupledto the upper edges of the first and second upright wall members 96, 98.The frame 32 may further include a mounting assembly 102 coupled to thecross beam 100 and to which the beam receiver 18 is mounted. Themounting assembly 102 may be adjustable about one or more axes in orderto position the beam receiver 18 at the focal point of the partialcircular paraboloid of the receive faces 56.

The optical isolation plate 90 may be positioned within the housingalong a horizontal plane at a level just above the receive base 58 ofthe receive reflection device 55. First, second, and third sides of theoptical isolation plate 90 may couple to the left side wall 80, thefront wall 84, and the right side wall 82, respectively. A fourth sideincludes a circular cutout that is slightly smaller than thecircumference of the receive base 58 of the receive reflection device55. Thus, the cutout of the optical isolation plate 90 is positionedbetween the edge of the receive base 58 and the receive faces 56. Sincethe optical isolation plate 90 overlaps the receive base 58, the plate90 acts as a shield to prevent stray radiation from the beam source 12being detected by the beam receiver 18.

The system 10 is generally implemented in a law enforcement vehicle 104,and the housing 26 may be mounted on the dashboard with access to anopen field of view. In various embodiments, the housing 26 may bemounted on the exterior of the vehicle 104, such as on the roof. In someembodiments, the camera 22 may be mounted on the exterior of the vehicle104 as well.

The system 10 may operate as follows. Referring to FIG. 13A, the system10, mounted in the law enforcement vehicle 104, may scan the fieldgenerally toward the front of the vehicle 104 for objects 28, such asother vehicles. The controller 20 may send a signal to the beam source12 and the motor 54 to initiate a scan of the field of view frame 32.Generally, once the system 10 is energized, the frame 32 is scannedrepeatedly, such that when one frame 32 is scanned, another frame 32begins scanning automatically.

Given a command from the controller 20, the beam source 12 generates abeam 30 that may have the power and pulse characteristics as describedabove. Also given a command from the controller 20, the motor 54 rotatesthe transmit reflection device 40. The beam 30 from the beam source 12may reflect off one of the transmit faces 42 and travel through thetransmit window 94 to the roadway or landscape in front of the lawenforcement vehicle 104. As the transmit reflection device 40 rotates,the transmit faces 42 rotate as well. Rotation of a transmit face 42while it is reflecting a beam 30 causes the beam 30 to sweep in thehorizontal direction across the field of view frame 32. The beam 30 maysweep from right to left or left to right depending on the direction ofrotation of the transmit reflection device 40. Once the edge of onetransmit face 42 rotates beyond the beam 30 from the beam source 12, thenext transmit face 42 reflects the beam 30 horizontally in the samedirection as the previous transmit face 42 did. The current transmitface 42 may sweep the beam 30 across the frame 32 at a different heightfrom the previous transmit face 42. Depending on the order in which thetransmit faces 42 are positioned on the transmit reflection device 40 orthe direction of rotation of the transmit reflection device 40, the beam30 reflected from the current transmit face 42 may sweep higher or lowerin the frame 32 than the beam 30 from the previous transmit face 42.

While the beams 30 are transmitted from the system 10 to the roadway infront of the law enforcement vehicle 104, one or more beams 30 may bereflected off of objects 28, as seen in FIG. 13B. The objects 28 may bemoving or stationary, on the road and off of the road. In addition, thelaw enforcement vehicle 104 and, in turn, the system 10 may bestationary or in motion.

As the beams 30 are reflected back to the system 10, the beams 30 may befocused by the receive reflection device 55 to the beam receiver 18.Since the receive base 58 of the receive reflection device 55 is coupledto the transmit base 44, the two devices 16, 40 rotate at the samespeed. In addition, the angle at which each receive face 56 is orientedcorresponds to the angle at which the vertically-aligned transmit face42 is oriented. For example, the transmit face 42 that sweeps the beam30 along the lowest horizontal path of the frame 32 is aligned with thereceive face 56 that is oriented to focus beams 30 reflected fromobjects located along the lowest horizontal path of the frame 32.Likewise, the transmit face 42 that sweeps the beam 30 along the highesthorizontal path of the frame 32 is aligned with the receive face 56 thatis oriented to focus beams 30 reflected from objects located along thehighest horizontal path of the frame 32.

The controller may use the timer circuit to determine the time of flightof pulses of the reflected beams 30 received by the beam receiver 18.Given the time of flight of the pulse and the speed of the pulse(roughly the speed of light), the distance to the object 28 from whichthe pulse of the beam 30 was reflected can be calculated. Furthermore,the controller 20 may determine the horizontal sweep angle θ at whichthe pulse of the beam 30 was transmitted from the transmit reflectiondevice 40. The controller 20 may assume that the pulse is reflected offan object 28 at the same angle it was transmitted. As a result, for eachpulse of the beam 30 received by the beam receiver 18, the controller 20determines the distance that the pulse traveled and the angle θ at whichthe pulse was reflected. Thus, the controller 20 may record the data foreach received pulse in terms of polar coordinates where the radius isthe distance to the object 28 from which the pulse was reflected and theangle is the angle θ at which the pulse was reflected. The controller 20may ignore data relating to pulses that are received near the horizontaledges of the frame 32, because that is where the beam 30 wastransitioning from one transmit face 42 to the next transmit face 42 andthe pulses may not be received properly at the edges of the frame 32.

The controller 20 may perform a plurality of calculations in order tocalculate the speed of objects 28 moving in the roadway in front of thelaw enforcement vehicle 104. The results of the calculations may berepresented in FIGS. 14-19. The controller 20 may not necessarilycommunicate the results of the calculations to the display 24 or othermonitor. However, the results are shown as graphs in the Figures to helpillustrate the operation of the controller 20.

The controller 20 may convert the data relating to received pulses ofthe beam 30 from polar coordinates to rectangular Cartesian coordinates,as shown in graph 106 of FIG. 14. Graph 106 depicts an overhead view ofthe roadway and the field of view of the system 10. The housing 26 ofthe system 10 may be located at coordinates (0, 0) of graph 106. Plottedalong the y-axis is the distance to the left (positive y direction) andto the right (negative y direction) from the housing 26 given in unitsof feet. Plotted along the x-axis is the distance away from the housing26 in front of the law enforcement vehicle 104 given in units of feet.The V-shaped lines 108 represent the boundaries of the sweep of the beam30. Received pulses of the beam 30 are raw data points 110 plotted ongraph 106 with a lower case x. In graph 106, a plurality of pulses areplotted that were received over a short period of time—perhaps onesecond.

Also shown in graph 106 are boxes 112 and circles 114 around clusters ofpoints 110 detected to be objects 28, as described in greater detailbelow. The sides of the box 112 may be drawn at the extents of theobject 28. The circle 114 may be drawn with its center located at themedian or the mean of the points 110 of the object 28.

In order to determine where objects 28 are in the plot of graph 106, thecontroller 20 may sort the points 110 by distance from the housing 26,as shown in the histogram plot of graph 116 in FIG. 15. Along the y-axisof graph 116 is plotted the number of points 110 received. Along thex-axis is plotted the distance from the housing 26. As seen from graph106 of FIG. 15, there is a large number of points 110 from the distanceof about 45 feet to the distance of about 70 feet. There is a smallernumber of points 110 from the distance of about 75 feet to about 90feet. There are very small amounts of points 110 occurring at greaterdistances from the housing 26. All the points 110 shown in graph 106 areplotted in graph 116 as the number of points 110 occurring at eachdistance away from the housing 26.

To enhance the detection of objects 28, a second set of points 118 mayalso be calculated and plotted. The second set of points 118 is, foreach distance, the sum of the number of points 110 for two feet oneither side of the distance. The value of two feet may be variable forother embodiments. For example, if the number of points 110 atconsecutive distances is given by: 8 feet=4 points, 9 feet=3 points, 10feet=6 points, 11 feet=5 points, and 12 feet=4 points. A second point118 for the distance of 10 feet would be the sum of the points 110 for 8feet to 12 feet=4+3+6+5+4. Thus, a second point 118 for 10 feet=22.

A threshold 120 is also applied to the second set of points 118, as seenin graph 116. The threshold 120 may have a constant value at a givennumber of points. In the example of graph 116, the constant value occursat approximately 410. The threshold 120 may also include an exponentialdecay that approaches an asymptote of zero points. For every group ofpoints 118 that crosses the threshold 120, there may be one or moreobjects 28.

To determine the number of objects 28 and the width of each object 28 ata certain distance, the controller 20 may sort the points 118 bydistance from the center at the certain distance from the housing 26.Thus, everywhere that there is a peak of the points 118 that crosses thethreshold 120, the controller 20 may sort the points 118 at the peak. Inthe example plot of graph 116, there are two peaks (a first at about 55feet and a second at about 80 feet) where the points 118 cross thethreshold 120. There is a third peak at about 135 feet where thethreshold 120 is almost crossed. The distribution of points 118 at thethree peaks are plotted as histograms in graphs 122, 124, 126 shown inFIGS. 16, 17, and 18 respectively.

The distribution of both sets of points 110, 118 at a distance ofapproximately 55 feet from the housing 26 is plotted in graph 122. Forreference, it can be seen in graph 106 that at a distance along thex-axis of about 55 feet, there is a plurality of points 110 positionedfrom about 4 feet to about 10 feet in the y direction. The raw datapoints 110 are plotted in graph 122 from 4 feet to 10 feet along thex-axis. The second set of enhanced data points 118 is also plotted ingraph 122. The threshold 120, with a value of approximately 35, isplotted as well. Thus, it appears from graph 122 that there is only oneobject at the distance of about 55 feet.

The distribution of both sets of points 110, 118 at a distance ofapproximately 80 feet from the housing 26 is plotted in graph 124.Similar to graph 122 discussed above, for reference, it can be seen ingraph 106 that at a distance along the x-axis of about 80 feet, there isa first plurality of points 110 positioned from about 14 feet to about20 feet in the y direction. There is a second plurality of points 110from about 12 feet to about 18 feet in the negative y direction. Thesepoints 110 are plotted in graph 124, showing one set of points 110between −18 and −12 and a second set of points 110 between 14 and 20.The second set of enhanced data points 118 is also plotted in graph 124.In addition, the threshold 120, with a value of approximately 15, isplotted. Thus, it can be seen that there are two objects 28 spaced about25 feet apart at a distance of about 80 feet from the housing 26.

The third peak from graph 116 is plotted in graph 126. As can be seen ingraph 106, at approximately 135 feet from the housing, there is a smallnumber of points 110 at about 10 feet and about 22 feet in the negativey direction. The raw data points 110 are plotted in graph 126 along withthe second set of enhanced points 118. As can be seen, the points 118fail to cross the threshold 120 of about 5.5. Thus, there is likely notan object 28 of any interest at a distance of about 135 feet from thehousing 26.

Once objects 28 are detected, the controller 20 may track them. Forevery object 28 that is detected, the controller 20 may create a track128. The track 128 represents the xy position of the median of points110 that were determined to be an object 28 from graphs 122, 124discussed above. A plot of tracks 128 is shown in graph 130 of FIG. 19.Graph 130 is similar to graph 106 in that it shows an overhead view ofthe roadway in front of the housing 26 which may be mounted in a lawenforcement vehicle 104. The lines 108 show the boundaries of the sweepof the beam 30. Three tracks 128 are shown in graph 130 that correspondto the three objects 28 of graph 106. The tracks 128 that are shown wererecorded over a period of time of a few seconds. Since the tracks 128represent the distance traveled by each object 28 and the period of timeis known, then the speed of each object 28 can be calculated as thedistance divided by the time. As can be seen, the upper and lower tracks128 of graph 130 do not cover much distance, and thus their speeds arenear zero. But, the middle track 128 travels a certain distance and hasa non-zero speed.

To determine the actual speed of the objects 28, the controller 20 mayreceive data from an accelerometer or from the pulse train of thetransmission of the law enforcement vehicle 104 to detect whether thevehicle 104 is moving. If the law enforcement vehicle 104 is moving,then the controller 20 may add or subtract the speed of the vehicle 104,as appropriate, to determine the actual speed of each object 28. If thelaw enforcement vehicle 104 is stationary, then the speed calculatedfrom the steps above is the actual speed.

Once the controller 20 has determined the speed of the objects 28 in theframe 32, the controller 20 may communicate the speed information to thedisplay 24. The display 24 may show an image from the camera 22 thatdepicts the field of view of the camera 22, which is generally the sameas the frame 32 that is being scanned by the system 10. The display 24may also show the speed data from the controller 20, such that objects28 on the display 24 have an associated speed. For example, a car may beseen on the display 24 with a box, a crosshair, or similar iconsuperimposed over the car with the speed of the car displayed nearby.The speed and the position of the icon may be updated as the object 28moves. Alternatively or in addition, the display 24 may have a splitscreen wherein the image from the camera 22 occupies one portion of thescreen and a data information area occupies another portion of thescreen. The image portion may still include an indicator of the speed ofeach car in motion. The data information portion may also list thespeeds of objects 28 as well as additional information on the objects 28or the system 10. The display 24 may further include touchscreencapabilities that allow the user to touch the screen to issue commandsto the system 10 or retrieve more information.

The traffic scanning LIDAR system 10 described herein offers a distinctadvantage over prior art LIDAR systems. Prior art LIDAR systems aim abeam at a single target and measure the difference between the time offlight of consecutive pulses. This approach measures the relative speedat which the target is moving toward or away from the LIDAR source. Therelative speed measured is the actual speed of the target if the targetis traveling on a path directly to or from the LIDAR source. If thetarget is traveling on a path away from the LIDAR source then themeasured speed is less than the actual speed of the target. Thisinaccuracy is known as the “cosine effect” or the “cosine error”. Thecurrent system 10 avoids the cosine error because the controller 20 isaware of the angle at which pulses are being reflected from objects 28(targets). Thus, the current system 10 can track the actual path of theobject 28, not just the path relative to the beam source 12. Determiningthe actual path of the object 28 results in calculating the actual speedof the object 28.

An additional advantage of the current system 10 over prior art systemsis that the current system 10 sweeps a beam 30 repeatedly over a fieldof view frame 32 and can therefore track a plurality of objects 28simultaneously. Prior art systems are generally not capable of sweepinga beam and are thus limited to tracking a single object 28.

The current system 10 is also capable of being used in otherapplications. The system 10 could be utilized in marine environments forspeed detection or navigation. The system 10 could also be utilized inrobotic applications for intelligent guidance and navigation ofself-propelled robots or robotic machinery. Furthermore, the system 10could be in the automotive or other vehicle industries for intelligentcollision-avoidance systems.

Although the invention has been described with reference to theembodiments illustrated in the attached drawing figures, it is notedthat equivalents may be employed and substitutions made herein withoutdeparting from the scope of the invention as recited in the claims.

Having thus described various embodiments of the invention, what isclaimed as new and desired to be protected by Letters Patent includesthe following:
 1. A system for determining the position and speed of aplurality of objects within a field of view, the system comprising: abeam source operable to generate a beam; a transmit reflection deviceoperable to reflect the beam at the plurality of objects, the transmitreflection device including a plurality of transmit faces, at least aportion of the transmit faces oriented at a different angle and operableto reflect the beam at a different height, wherein the beam reflectionoff each transmit face creates a sweep; a beam receiver operable todetect the beam; a receive reflection device including a plurality ofreceive faces, at least a portion of the receive faces oriented at adifferent angle and operable to focus the beam reflected from theplurality of objects at different heights onto the beam receiver; and acontroller operable to (1) repeatedly perform a plurality of sweepswithin the field of view to track each of the plurality of objectswithin the field of view, and (2) determine the position of each of theplurality of objects over time and calculate the speed of each of theplurality of objects based on a change in the position of the objects.2. The system of claim 1, wherein the transmit faces are oriented atconsecutively varying angles from a first transmit face to a lasttransmit face to reflect the beam at consecutively varying heights. 3.The system of claim 2, wherein the angle of each transmit face changesby the same amount for consecutively positioned transmit faces.
 4. Thesystem of claim 2, wherein each transmit face is oriented at an angledifferent from each of the other transmit faces.
 5. The system of claim1, wherein the transmit reflection device further includes a disc-shapedbase and a disc-shaped upper stage spaced apart from and of a smallerdiameter than the base, the transmit faces being positioned in a circlebetween the upper stage and the base at an angle therebetween.
 6. Thesystem of claim 5, wherein the transmit reflection device is rotatableabout a central axis such that the beam reflects off each transmit facein turn as the transmit reflection device rotates to create said sweep.7. The system of claim 6, wherein the sweep reflected from the firsttransmit face to the last transmit face overlap one another.
 8. Thesystem of claim 1, wherein each receive face includes an outer surfacewith a shape operable to focus beams reflecting from the plurality ofobjects.
 9. The system of claim 8, wherein the shape of the outersurface of each receive face is a partial circular paraboloid.
 10. Thesystem of claim 1, wherein the receive reflection device furtherincludes a disc-shaped base and a disc-shaped upper stage spaced apartfrom and of a smaller diameter than the base, the receive faces beingpositioned in a circle between the upper stage and the base at an angletherebetween and the angle changes by the same amount for consecutivelypositioned receive faces.
 11. The system of claim 10, wherein thereceive reflection device is rotatable about a central axis of the baseand the upper stage, such that each receive face focuses beams atdifferent heights as the receive reflection device rotates.
 12. A systemfor determining the position and speed of an object within a field ofview, the system comprising: a beam source operable to generate a beam;a transmit reflection device operable to reflect the beam at the object,wherein each transmit reflection device includes a plurality of transmitfaces, wherein each transmit face is oriented at an angle, wherein atleast a first portion of the transmit faces is oriented at a differentangle than a second portion of the transmit faces, such that the firstportion of the transmit faces is operable to reflect the beam at adifferent height than the second portion of the transmit faces; a beamreceiver operable to detect the beam; a receive reflection deviceincluding a plurality of receive faces, wherein each receive face isoriented at an angle, wherein at least a first portion of the receivefaces is oriented at an angle corresponding to the angle at which thefirst portion of the transmit faces is oriented, and a second portion ofthe receive faces is oriented at an angle corresponding to the angle atwhich the second portion of transmit faces is oriented, such that thereceive reflection device is operable to focus the beam reflected fromthe plurality of objects at different heights onto the beam receiver;and a controller operable to determine the position of the object overtime and calculate the speed of the object based on a change in theposition of the object.
 13. The system of claim 12, wherein the transmitfaces are oriented at consecutively varying angles from a first transmitface to a last transmit face to reflect the beam at consecutivelyvarying heights.
 14. The system of claim 13, wherein the angle of eachtransmit face changes by the same amount for consecutively positionedtransmit faces.
 15. The system of claim 13, wherein each transmit faceis oriented at an angle different from each of the other transmit faces.16. The system of claim 12, wherein the transmit reflection device isrotatable about a central axis such that the beam reflects off eachtransmit face in turn as the transmit reflection device rotates, and thebeam reflection off each transmit face creates a sweep, wherein thesweep reflected from the first transmit face to the last transmit faceoverlap one another, and wherein the receive reflection device isrotatable about a central axis of the base and the upper stage, suchthat each receive face focuses beams at different heights as the receivereflection device rotates.
 17. The system of claim 12, wherein eachreceive face includes an outer surface with a partial circularparaboloid shape operable to focus beams reflecting from the pluralityof objects.
 18. A method for determining the position and speed of anobject within a field of view, the method comprising the steps of:generating a beam; projecting the beam towards a transmit reflectiondevice operable to reflect the beam at the object, wherein said transmitreflection device includes a plurality of transmit faces, wherein eachtransmit face is oriented at an angle, and at least a first portion ofthe transmit faces is oriented at an angle different from an angle oforientation of a second portion of the transmit faces; detecting areflection of the beam at different heights dependent on the transmitface off of which the beam reflected; generating a sweep of the objectby rotating the transmit faces as the beam is projected towards theobject; repeatedly generating a plurality of sweeps within the field ofview to track the object within the field of view; determining theposition of the object over time based on the plurality of generatedsweeps; and calculating the speed of the object based on a change in theposition of the object.
 18. The method of claim 18, wherein prior todetecting a reflection of the beam at different heights, the methodfurther includes the steps of: receiving, at a receive reflection devicehaving a plurality of receive faces and wherein at least a portion ofthe receive faces is oriented at a different angle, the beam reflectedby the transmit reflection device; focusing the beam received at thereceive reflection device at different heights onto a beam receiver; andperforming said step of detecting a reflection of the beam at differentheights.
 19. The method of claim 18, wherein a portion of each sweepreflected from a first transmit face to a last transmit face overlapsthe sweeps adjacent thereto.
 20. The method of claim 19, wherein thetransmit faces are oriented at consecutively varying angles from a firsttransmit face to a last transmit face to reflect the beam atconsecutively varying heights, and wherein the angle of each transmitface changes by the same amount for consecutively positioned transmitfaces.